Patrick McDermott/GettyMLB commissioner Bud Selig, left, and Michael Weiner, right, were on hand in New York today to announce a new labor agreement between major-league owners and players.

NEW YORK — Baseball players and owners signed an agreement for a new labor contract today, a deal that makes baseball the first North American professional league to start blood testing on human growth hormone and expands the playoffs to 10 teams by 2013.

An initial positive test for HGH would result in a 50-game suspension, the same as a first positive urine test for a performance-enhancing substance.

"This was very important to me," baseball commissioner Bud Selig said. "This really is in everyone's best interest."

Random testing for HGH will take place during spring training and the offseason, but there is no agreement yet on random testing in-season. There can be testing at any time for cause.

"We've consulted with a lot of scientists on this, and we know there's a difference of opinion among scientists we've consulted," union leader Michael Weiner said. "We are sufficiently comfortable with the science to go ahead with testing, but we have preserved the right if there is a positive test for there to be a challenge — if that's appropriate — to the science at that point in time."

The sides will explore in-season testing, but the union wants to make sure it's done in a way that doesn't interfere with players' health and safety.

"The players want to get out and be leaders on this issue, and they want there to be a level playing field," Weiner said. "The realities, though, are that baseball players play virtually every single day from Feb. 20 through October. And that's unlike any other athlete — professional or amateur — who's subject to drug testing. We want to make sure that we're doing everything we can on the HGH issue, but that it be consistent with not interfering with competition and not interfering with players health and safety under those circumstances."

At a time when the NBA season is threatened by a lockout and NFL preseason was disrupted by labor strife, this deal ensures baseball will have 21 consecutive years of labor peace since the end of the 1994-95 strike.

"Nobody back in the '70s, '80s and early '90s, 1994, would ever believe that we would have 21 years of labor peace," Selig said.

The deal, which still must be ratified by the players and owners, is the first contract since Weiner replaced Donald Fehr as union leader last year.

As for the playoffs, there will be an additional two teams starting in 2012 or 2013 that will give baseball 10 of 30 clubs in the postseason. In the NFL, 12 of 32 teams make the playoffs. In the NBA and NHL, 16 of 30 advance.

The two wild cards in each league — the non-first place teams with the best records — will meet in a one-game playoff, and the winners will move on to the division series.

This agreement calls for the Houston Astros to switch from the NL Central to the AL West in 2013, leaving each league with three five-team divisions. It's baseball's first realignment since the Milwaukee Brewers went to the NL after the 1997 season.

On the economics, the threshold for the luxury tax on payrolls will be left at $178 million in each of the next two seasons, putting pressure on high-spending teams such as the Yankees, Boston Red Sox and Philadelphia Phillies not to raise their spending even more. The threshold rises to $189 million for 2014-16.

The minimum salary reaches the $500,000 mark in 2014, and then there will be cost-of-living increases in both of the following two years. There will also be a new "competitive balance lottery" that gives small-market teams extra selections in the amateur draft.

Major league free agent compensation will be completely revised in 2013, with a team having to offer its former players who became free agents the average of the top 125 contracts — currently about $12 million — to receive draft-pick compensation if a player signs with a new team. It eliminates the statistical formula that had been in place since the 1981 strike settlement.

In addition, the portion of players with 2-3 years of major league service who are eligible for salary arbitration will rise from 17 percent to 22 percent starting in 2013.

And there a new market disqualification test, preventing teams from large markets from receiving revenue-sharing proceeds — and lowering the amount the big teams pay as long as they stay under the payroll threshold.

Owners achieved their goal of reining in spending on amateur players coming to the major leagues. For high school and college players taken in the June amateur draft, there will be five bands of penalties, starting with a 75 percent tax on the amount 0-5 percent over a specified threshold for each team next year, based on its selection spot. For teams going 5-10 percent over, the tax will rise to 100 percent and they will lose their next first-round draft pick. If a team goes more than 15 percent over, it could lose its following two first-round draft picks.

For players taken in the 11th round and beyond, teams may give them signing bonuses up to $100,000 without it counting against the new threshold.

For international amateur signings from nations such as the Dominican Republic and Venezuela, a luxury tax will begin with the July 2012-June 2013 signing season.